Cooling tank



Aug. 22, 1950 H. G. MoJoNNlER COOLING TANK 2 Sheets-Sheet 1 Filed May 3,1946 Aug. Z2, 1950 H. G. MoJoNNlER COOLING TANK 2 Sheets-Sheet 2 FiledMay 3, 1946 Patented Aug. 22, 1950 UNITED STATES PATENT OFFICE lCOOLINGTANK Harry G. Mojonnier, Oak Park, Ill.

Application May 3, 1946, Serial No. 667,227

11 Claims.

The present invention pertains in general to refrigerating apparatus andin particular to improvements in evaporator or cooling tank structuresemployed in such apparatus, wherein the fluid being cooled flows throughelongated tubes forming a part of the evaporator.

In certain forms of cooling or evaporating apparatus, the fluid orliquid to be cooled is caused to pass through tubes or like confinedpassages while subjected to the action of a refrigerant.

Due to inattention of operating personnel, it is possible that anapparatus of this type may be damaged due to freezing of the liquidbeing cooled within the tubes. As is well known, the volume of a frozenliquid increases as it changes to the solid state. This expansion of thefrozen liquid produces large stresses which may be sufiicient to rupturethe tube through which such uid normally flows. Even in the absence ofdamage to the apparatus, such freezing is extremely detrimental in thata considerable loss of time is incurred in thawing the frozen fluid torestore the apparatus to normal operating condition.

It is an object of the present invention to provide an improved coolingapparatus of the above type wherein provisions are made to minimize theprobability of freezing of the fluid being cooled.

Another object of the invention is to provide an improved coolingapparatus having means for preventing damage to the cooling tubestherein,

in the event that the uid flowing through such i tubes freezes.

A further object of the invention is to provide an improved coolingapparatus incorporating means for enabling rapid thawing of the fluidbeing cooled, in the event that such fluid freezes in the apparatus.

Still another object of the invention is to provide a cooling apparatus,in accordance with the preceding objects, in which the means forminimizing the probability of freezing of the fluid being cooled alsoserves to increase the operating efficiency of the structure.

The above objects of the invention, together with further objects andadvantages thereof, will best be appreciated and understood upon aperusal of the specification herein taken in conjunction with thcaccompanying drawings, in which:

Fig. 1 is a general layout, diagrammatic in form, of a cooling systemincorporating an evaporator which is constructed in accordance with theprinciples of the invention,

Fig. 2 is an enlarged side elevational view, partly in section, of theevaporator unit included in Fig. 1,

Fig. 3 is a top View of the evaporator shown in Fig. 2 with a portionbroken away to disclose the cooling tubes therein,

Fig. 4 is a detailed sectional view illustrating one form ofconstruction of the evaporator tubes, and associated freeze protectivemeans,

Figs. 5 and 6 are cross sectional views of the tubes illustratingalternative forms of construction of the freeze protective means,

Fig. 7 is a detailed sectional view illustrating a further form ofconstruction of the freezing protective means, and

Fig. 8 is a cross sectional view taken along the line 8-8 of Fig. 7.

In the embodiment of the invention disclosed in Figs. 1-4, there isshown a cooling system, Fig. l, comprising an evaporator I through whicha refrigerant is circulated by a compressor 2 through a condenser 3, aninjector 4 and a back pressure regulating valve 5. The liquid or fluidto be cooled is admitted to the evaporator through a pipe 6 and iswithdrawn from the evaporator through a pipe 1. As may best be seen inFig. 2, the fluid to be cooled flows through a series of tubes 8extending between header chambers 9 and I0 located at the top and bottomof the evaporator I. The refrigerant, which enters the evaporatorthrough injector nozzle d' in liquid form, and leaves through the valve5 in gaseous form, flows along the outer walls of such tubes. Each ofthe tubes 8, through which the fiuid to be cooled flows, has a freezeprotective member II extending therethrough from the top to the bottomlof evaporator I. As will be later de scribed, these members may be solidcylinders of resilient material, but in the embodiment of Figs. 1-4 aretubular in form in order to enable hot air or hot water to be circulatedtherethrough to thaw out the tubes 8 in the event of freezing. Hot watermay be admitted to tubes I I by means of a faucet I2, located above theevaporator I. and may be collected by a drip pan I3, located beneath theevaporator. The tubes I I are preferably of thin walled structure, for apurpose later to be described.

Referring now in particular to Fig. 2, the evaporator I may be of thegeneral type disclosed in my copending application, Serial No. 671,650led May 22, 1946, and comprises an outer cylindrical casing I4 withinwhich an inner casing I5 is concentrically located. The space betweenthe casings I4 and I5 is filled with insulating material I8, which maybe cork or the like. The inner casing I extends between a pair of tubesheets Il and I8 to which it is secured by welding or the like. Each ofthe tube sheets has a series of circular openings extending therethroughhaving annular spaced grooves therein. The tubes I extend between thesheets I1 and I8, to which they are secured by rolling grooves thereinwhich engage the annular spaced grooves in the circular openings. All ofthe tubes 8 are encased within an inner casing I 9 extendingsubstantially the entire length between', but terminating somewhat shortof, the tube sheets I1 and I8. The lower end of casing I8 is providedwith a turned-out flange 20 which engages the inner wall of casing I5and is secured thereto by welding or the like.

When the refrigerant enters the evaporator through the injector 4, itflows upwardly within the casing I9 and surrounds the cooling tubes 8.As the refrigerant flows over these tubes a heat transfer takes placebetween the fluid being cooled and the refrigerant, causing the latterto be vaporized. A portion of the refrigerant will flow over the top ofcasing I9 and fall between such casing and the inner wall of casing I5and thence will be recirculated through Venturi action oi.' the injector4. The level of the liquid refrigerant in the evaporator is normallymidway between the headers 9 and I0, the space above the level of theliquid consisting chiefly of vaporized refrigerant. The vapor leaves theevaporator through pipe 2 I, which extends to the back pressureregulating valve 5 shown in Fig. l, and is compressed by compressor 2,and then is cooled and liquified in condensvr 3 in a recirculationcycle. Casing I9 is pro l'ided with a baille 22 which encloses theentrance to pipe 2I on all but the lower side in order to prevent liquidrefrigerant from entering the pipe.

The upper header chamber 9 is formed by a dome-shaped cap member 28secured to the upper tube sheet I'I by means of bolts, such as 2l,extending through openings in an outwardly turned flange of the cap intothreaded holes in the tube sheet. The junction between the tube sheetand cap member is sealed by a gasket 25. A similar dome-shaped capmember 26 is secured to the tube sheet I8 in like manner to form thelower header chamber I0. As will be understood, the liquid or fluid tobe cooled` such for example as water, enters the upper header chamber 8by means of a pipe 6, and flows downwardly through the parallelconnected tubes 8 into the lower header chamber I0. from which it iswithdrawn through the outlet pipe 1.

As previously stated, and as best shown in Fig. 4, each of the tubes 8is provided with a freeze protective tube II disposed therein in annularspaced relationship. As also previouslv stated, in the embodiment ofFigs. 1 4, the tubes Il are circular in cross section and extend throughthe dome-shaped cap members 23 and 26, suitable packing glands, asindicated at 21, being provided to insure a fluidtight connection andprevent leakage of liquid from the header chambers. As best shown inFig. 2, the cap member 28 is provided with an upwardly projectingannular rim 28 forming a distributor well from which hot water may bedistributed from the faucet I2 for passage downwardly through the tubesI I into the drip pan I3.

In operation, it will be seen that due to the provision of the tubes I Iwithin the cooling tubes 8, the fluid to be cooled in its passagethrough the tubes 8 is caused to move therethrough in the form of anannular film within the passage 28, Fig. 4, provided between the tubes.By this means the speed of flow of the cooled liquid or fluid isincreased while in thermal contact with the walls of the tubes 8 andwith the refrigerant. producing a high thermal efficiency. Also, theenforced passage of the fluid through the tubes in the form of anannular fllm along the tube surfaces causes the tube surfaces to becontinuously wiped by the flowing fluid, preventing stagnation or theformation of insulation pockets. In instances wherein liquid ows througha tube in a solid circular body, the rate of flow along the center ofthe tube may be greater than that along the tube walls, due to friction.By reason of the present arrangement wherein the liquid flows as a fllmthrough the annular passage 28 a substantially constant flow rate of allof the liquid is insured. This movement of the liquid through the tubes8 in the form of a film promotes high thermal efficiency of the unit, asstated, and also minimizes the probability of freezing of the liquidwithin the tubes.

As previously stated, the freeze protecting tubes II are of relativelythin walled structure. Thus, the cooling tubes 8 may, for example, beformed of stainless steel tubing having a wall thickness, in anillustrative example, of .054. On the other hand, the tubes II may beformed of relatively softer brass tubing, having a wall thickness of.015". As will be understood, the foregoing dimensions are set forth byway of illustration and not by way of limitation.

Due to the relatively thin walled character of the freeze protectivetubes I I, in the event the liquid within the annular passages 29should, through inadvertence of the operator, freeze solid and expand,said tubes I I will yield, thereby protecting the cooling tubes 8 frombreakage. When freezing of the fluid being cooled occurs, the eifectiveinner diameter of cooling tubes 8 decreases progressively as freezingcontinues due to the fact that ice forms on the inner walls of tubes 8first and the depth of such ice formation gradually increases. Thepresence of such an ice formation may be detected by observing thechange which occurs in the rate of flow of the fluid being cooled, or bynoting the change which occurs in the difference in pressure between theentrance and exit points of such fluid. Upon noting such a change, stepsmay be taken immediately to remedy the cause and to thaw the iceformation before complete stoppage of flow occurs. The tubes II provideready means for effecting thawing of the ice formed within the annularpassages 2S, which ice either wholly or partially blocks such passages,in that hot water or air may be readily passed through tubes I I fromthe faucet I2 or otherwise, to effect thawing of the frozen uid. Theclose proximity of the freeze protective members to the ice formationenables such formation to be thawed without unduly raising thetemperature of the refrigerant. By this means the shut-down time of theevaporator, in the event of freezing, is minimized. As will beunderstood, the slight collapse of the tubes II, to accommodate theexpansion due to freezing, does not stress the metal beyond the elasticlimit.

Ordinarily the thin walled tubes II, even if of circular cross section,as in Figs. 1-4, will yield sufficiently to accommodate the expansion ofthe freezing liquid. In certain instances, however, it may be desirableto provide a special configura- 5 tion of the tube cross section topromote yielding in the event freezing takes place.

Various alternative forms of construction of the freezing protectivemembers are shown in Figs. -8. In Fig. 5 a structure is shown whereinthe tube lla, corresponding in function to the tube Il previouslydescribed. has that portion thereof which is disposed within the tube 0of generally oval cross section as shown. Such oval cross sectionfacilitates the yielding of the tube when subjected to the ice pressure.As will be understood, the ends of the tubes Ila, where they passthrough the cap members, will preferably be retained in circular crosssection, as indicated at Il, to facilitate application of the packingglands and connections 21, Fig. 2.

When the tube ila is provided with an oval configuration, as shown inFig. 5, the tube t may be similarly ovalled, if desired, to retain arelatively thin oval uw eway between the tubes, for the reasonspreviousb set forth.

In Fig. 6 the tube IIb. corresponding to the tube il, as previously setforth, is provided with flutes or grooves, as indicated at l2, alongthat portion of the tube length which is disposed within the tube l, tofacilitate shifting of the tube wall when subjected to ice pressure.

In Figs. 7 and 8 a still further embodiment is set forth wherein thefreeze protective member llc is in the form of a solid rubber blockyieldable to accommodate ice expansion. When the freeze protectivemembers are of solid construction they need not extend through the capmembers 23 and 28, and consequently may be supported by the tube sheetsI1 and I8, or by the Y tubes l, in any suitable manner.

It is obvious that various changes may be made in the specificembodiments set forth for purposes of illustration without departingfrom the spirit of the invention. The invention is accordingly not to belimited to the precise embodiments shown and described, but only asindicated in the following claims.

The invention is hereby claimed as follows:

1. A cooling unit for use with refrigerating apparatus comprising a tankstructure, a first set of elongated passages extending through the tankstructure, a second set of elongated passages each extending through thetank structure adjacent to and in heat exchange relationship with acorresponding passage of said first set. said first set of passagesbeing adapted to transmit a fluid to be cooled and means forrecirculating a refrigerant medium within said tank structure in heatexchange relationship with said medium to be cooled, said second set ofpassages enabling a heated medium at times to be transmittedtherethrough in thermal contact with the medium being cooled in order tothaw such medium in the event that it becomes frozen within said firstset of passages, and said second set of -passages having a wall strengthresistant to pressure materially less than the strength of said firstset of passages whereby to absorb stresses produced when said fluidfreezes.

2. A cooling unit for use with refrigerating apparatus comprising a tankstructure, a first set of elongated es extending through the tankstructure, a second set of elongated passages each extending lengthwisethrough a lcorresponding passage of said first set, said first set ofpassages being adapted to transmit a iiuid to be cooled and means forrecirculating a refrigerant medium within said tank structure in heatexchange relationship with said medium to be 6 cooled, said second setof passages enabling a heated medium at times to be transmittedtherethrough in heat exchange relationship with the medium being cooledin order to thaw such medium in the event that it becomes frozen withinsaid first set of passages and said second set of passages having a wallstrength resistant to pressure materially less than the strength of saidfirst set of passages whereby to absorb stresses produced when saidfluid freezes.

3. A cooling unit for use with refrigerating apparatus comprising a tankstructure, a first set of tubes extending through the tank structure, asecond set of tubes each extending through the tank structure within acorresponding tube of said first set, said first set of tubes beingadapted to transmit a fluid to be cooled, and means for recirculating arefrigerant medium within said tank structure in heat exchangerelationship with said medium to be cooled, said second set of tubesbeing resilient and having a strength rel sistant to pressure materiallyless than said first set of tubes whereby to absorb the stresses whichwould otherwise be produced in said first set of tubes when freezingoccurs therein and thereby preventing injury to the first set of tubes.

4. A cooling unit for use with a refrigerating apparatus comprising atank structure, said tank structure being formed with header chambers atopposite ends thereof, a plurality of tubes arranged in parallel withinthe tank structure, said tubes extending between and communicating withsaid header chambers and being adapted to transmit a fluid to be cooledtherebetween, means for recirculating refrigerant within the tankstructure into engagement with the outer surfaces of the walls of saidtubes to effect cooling thereof, and a plurality of pipes associatedrespectively with said tubes, said pipes extending through the tubes andthrough said header chambers whereby the passages within said pipes areaccessible externally of the tank structure for the reception of a fluidto be passed therethrough.

5. A cooling unit for use with refrigerating apparatus comprising a tankstructure, said tank structure being formed with header chambers atopposite ends thereof, a plurality of tubes arranged in parallel withinthe tank structure, said tubes extending between and communicating withsaid header chambers and being adapted to transmit a fluid to be cooledtherethrough, a casing encompassing said tubes, said casing being spacedinwardly from the side walls of the tank structure, means forrecirculating refrigerant through said casing and through the chamberdefined between the casing and the side walls of the tank so as to bringthe refrigerant into thermal engagement with said tubes, and a pluralityof pipes extending respectively through said tubes and through theheader chambers, said pipes having a strength resistant to pressurematerially less than the tubes, and said pipes forming passages for thetransmission of a heating medium therethrough to effect the heating ofiiuid within the tubes.

I6. In a cooling apparatus, means for transmitting a fluid which is tobe cooled, said transmitting means including a tube over one surface ofwhich said iiuid flows, a pair of tube sheets supporting the oppositeends of the tube, refrigerant circulating means for cooling the othersurface of said tube to thereby extract heat from said fluid, resilientmeans comprising a metal tube extending longitudinally of said firstmentioned tube of a strength resistant w pressure materially less thanthat of said first mentioned tube and spaced from one surface of saidfirst mentioned tube, the space between said one surface of said rstmentioned tube and said resilient means defining a channel through whichsaid fluid flows, said resilient means serving to absorb stresses whichwould otherwise be produced by freezing of said fluid in said channel,said resilient means being shaped to provide a passage through which aheating material may be passed for heating said resilient means to thawuid frozen in said channel, and a pair of tube sheets disposed outwardlyof said first named tube sheets and supporting the opposite ends of saidresilient means.

7. In a cooling apparatus, transmission means for a fluid which is to becooled, said transmission means including a' tube through which saidfluid flows, a pair of tube sheets supporting the opposite ends of thetube, refrigerant circulating means for cooling the outer surface ofsaid tube to extract heat from said fluid, a resilient member disposedwithin and extending lengthwise of said tube and shaped to conform tothe inner wall of said tube and disposed closely adjacent thereto,whereby the fluid flows in a thin film along said inner wall, saidmember having a wall surface of a strength resistant to pressurematerially less than the strength of the tube, whereby to absorbstresses which would otherwise be produced in said tube and which wouldresult in injury thereto when said fiuid freezes, and a pair of tubesheets disposed outwardly of said first named tube sheets and supportingthe opposite ends of said resilient member.

8. In a cooling apparatus, transmission means for a fluid which is to becooled, said transmission means including a plurality of tubes throughwhich said fluid flows, means for cooling the outer 40 surface of saidtubes to extract heat from said fluid, and a hollow resilient memberdisposed 8 within and extending lengthwise of each 0f said tubes, eachsaid member having a wall surface of a strength resistant to pressurematerially less than the strength of its associated tube whereby toabsorb stresses which would otherwise be produced in said tube when saiduid freezes, and said member being arranged to receive a heatedrfieiiiiium to effect rapid thawing of such frozen 9. A cooling unit foruse with refrigerating spparatus comprising a tank structure, aplurality of tubes arranged in parallel within v the tank structure,said tubes being adapted to transmit a fluid to be cooled, means forrecirculating a cooling medium within said tank so as to bring saidcooling medium intolheat exchange relstionship with said tubes, and aplurality of pipes extending respectively longitudinally through saidtubes and through the wall of said tank structure, said pipes having astrength resistant to pressure materially less than said tubes.

10. A cooling unit as defined in claim 3, wherein the tubes of saidsecond set are oval shaped in transverse cross section.

l1. A cooling unit as defined in claim 3, wherein each of the tubes ofsai'd second set has a longitudinally extending groove to facilitate thedeformation thereof responsive to applied pressure.

HARRY G. MOJONNIER.

REFERENCES CITED The following references are of record in the me ofthis patent:

UNITED STATES PATENTS Great Britain Nov. 1, 1934

